Process of making adhesive tapes



Patented May as, .1943 It 2,319,933

UNITED STATES PATENT OFFlCE PROCESS OF MAKING ADHESIVE TAPES Earl G. Kerr, Leonia, N. J., assis'nor, by mcsne assignments, to Allied Chemical & Dye Corporation, a corporation of New York No Drawing. Application May 25, 1940,- Serial No. 337,200

. 2Claims. (01117-122) This invention relates to adhesive tapes and utiiized.- In carrying the invention into effect, more particularly to adhesive tapes, the adhesive 1 the paracoumarone resin may be melted until it of which is of the pressure-sensitive type. is fluid and then stirred with the chlorinated There are employed for numerous purposes, for rubber until the resin and rubber are intimately example in painting and finishing automotive ve- 5 blended and produce a homogeneous mixture. hicle bodies, adhesive tapes constituted of a cellu- Paracoumarone resin. as is well known, is made lose or fabric backing and a layer of pressureby polymerizing constituents such as coumarone sensitive adhesive involving rubber containing a and indene present in coal tar naphtha. Resins volatile solvent. The use of transparent regenmade by the po merization o dis i ate-i oberated cellulose (known in the trade as "Cellol tained from petroleum and natural gas including phane") tapes has in recent years found wide cracked distillates h P p i Similar to the application. One diiiliculty accompanying the properties oi paracoumaronc resin and may-be use of such adhesive tape has been the tendency employed in lieu of paracoumarone resinin pracof the adhesive eventually to dry out and lose its ticing the invention. tacky characteristics owing to evaporation of 1 As illustrative of the invention, the following the solvent. Furthermore. in the case of transexamples are given:

parent regenerated cellulose, it has been found Emmle I that some ofthe adhesives heretofore proposed v present the added dimculty of not bonding satis- A blend 0 paracoumarone resin, constituted fact-only t t cellulose b 0f 47 parts by weight Of 8811! having a softening It is an object of the invention to provide a P0111t (T1118 and ball) 01 bo t 2 11N14 parts pressure-sensitive adhesive tape constituted of a by weight 91 Pereeoumamne resin having a backing and an improved pressure-sensitive acltiming P011? (11118 and ball) 0! about C-. hesive, which blend had a softening point (ring and It is a further object of this invention to proball) about w heated n i he r sin vide an improved pressure-sensitive adhesive subblend wesae mobile liquldr Parts y l s'tantially free from volatile solvents and which is welght 1 =hlorinated rubber having chlorine; not subject to loss of its tacky pressure-sensitive content of 65 to 63 P cent Were added to h characteristics owing to evaporation of solvent. liquid resin and the mixture it d ntil Other objects and advantages willappear here; a homogeneous productwasobtained. The para- )mmen coumarone resin was blended with the chlorin- I have found that by blending paracoumarone rubber ate temperature belOW about C" resin of a softening point of 50 0. or lower with Preferably within the maze of from 40 to 100 C. chlorinated rubber a substantially permanently to avoid decommsmon of h chlorinated rubbertacky pressure-sensitive adhesive mass is ob- This blend was applied in heated condition to tained which maybe employedfor coating celluface "cellophane" strip to Produce adhesive lose, fabric or other flexible backing to produce tape- The adhesive mating 0f thiltepe Possessed pressure-sensitive adhesive tape. 'The adhesive pressure'sensmve adhesive chemtel'lsties and is substantially free iroin volatile solvent and did not lose its tacklness upon Prolonged exhence is not subject to loss of tackiness by sol- 40 posm'e to The tape may be Wound in r0118 vent evaporation. As the chlorinated -rubber with adhesive on the inner 8 0f constituent of the adhesive, the chlorinated rubeach in a manner Well known l h ber containing from to per cent of chlorine adhesive tape m 30w obltaireigble under the name "Torneait" may ggg h xggg g g z g lf a 6 amp 0y v on are as The ratio of paracoumarone resin to chlorin- 9" parts being by weight: ated rubber in the adhesive may be varied from Q Examples about 1 to about 20, preferably from 5 to 10 parts 1 by weight of the resin to 1 part of the chlorinated I n m rubber, depending on the tackiness which it is i desired to impart to the adhesive and the properm 19 m ties such as the'softeningiwint of the resin and 49 ,ihfifima ball) on the rubber. The degree of tackiness of the adg i g :g fi} hesive may be varied by varyinl; he lof nins 3 z l nd ulg 9o point of the resin employed o v ins the P 55 Total 100 loo loo portions of the resin and chlorinated rubber The 31 C. softening point resin of Example IV was made by blending '70 parts of 7 C. sofby weight of 111 C. softening point resin: The 39 C. softening point resin of Example V was made by blending 66 parts of 7 C. softening point resin with 18 parts of 111 Cpsoftenin point resin. The above adhesive compositions were applied as adhesive to flexible backing strips to produce adhesive tapes.

If desired plasticizers such as dibutyl phthalate,

tricresyl phosphate, amyl stearate, ethyl abietate,

and methyl cyclohexanol adipate may be employed, preferably .in small amounts, in the com- 7 position.

i From the above description of the invention, it will be seen that I have provided novel pressure-sensitive adhesive tapes constituted of a flexible base, preferably a transparent regenerated cellulose base; and an adhesive consistin of paracoumarone resin of a softening point of 50 C. or lower and chlorinated rubber, which adhesive is substantially permanently tacky-and is not subject to hardening and loss of tackiness by evaporation of volatile solvent upon exposure to the air and maybe of sufliciently light color for use on light colored tapes. It is to be understood that the reference herein to 'paracoumarone resin of a softening point of not over 50 C. is intended to include blends of resins or of resins and plasticizers which blends have a' softening point not over about 50 C. although individual constituents of the blends, as in Examples IV and V have softening points above 50 C. The adhesive has characteristics which make it especially suitedjor uses in which a teningpoint paracoumarone'resin with 20 parts pressure-sensitive,

1. A process of making substantially permanently tacky, pressure-sensitive tape which comprisesheating together from 1 to 20 parts by weight of paracoumarone resin of a softening point not substantially above C. (ring and ball) and 1 part byweight of chlorinated rubher having a chlorine content of from about to '70 per cent, and applying this blend consisting substantially entirely of paracoumarone resin and chlorinated rubber in heat-liquefied condition substantially free from volatile sol-f vent to a flexible backing.

2. A process of making substantially permanently tacky, pressure-sensitive adhesive tape which comprises heating together from 5 to 10 parts by weight of paracoumarone resin of a softening point (ring and ball) not substantially above 50 C. with 1 part by weight of chicrinated rubber having a chlorine content of from about 65 to per cent to form a homogeneous blendof the resin and chlorinated rubber, and applying this blend consisting substantially entirely of said paracoumarone resin and chlorinated rubber and substantially free from volatile solventin heat-liquefied condition to a flexible backing.

EARL G. KERR. 

